Method for generating a preamble sequence group

ABSTRACT

Provided is a method for generating a preamble sequence group. The method includes creating a preamble sequence, calculating a cross-correlation value between sequences using the created preamble sequence, determining a limit cross-correlation value using the cross-correlation value to construct a preamble set used in the communication system, calculating a preamble set that satisfies the determined limit cross-correlation value, and terminating construction of the preamble set.

PRIORITY

This application claims priority under 35 U.S.C. § 119 to an application entitled “Method for Generating Preamble Sequence Group” filed in the Korean Intellectual Property Office on Oct. 27, 2003 and assigned Serial No. 2003-75271, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method for generating a preamble set or group in a communication system and an apparatus adopting the method, and in particular, to a method for generating an optimal preamble set using a plurality of sequences used to increase the limited number of channels, and an apparatus adopting the method.

2. Description of the Related Art

Generally, communication systems support communication services and include transmitters and receivers.

FIG. 1 is a block diagram of a general communication system. Referring to FIG. 1, a transmitter 10 and a receiver 20 provide communication services using frames. The transmitter 10 and the receiver 20 need to acquire synchronization information for accurate transmission and reception of the frames.

In order to acquire the synchronization information of the receiver 20, the transmitter 10 transmits to the receiver 20 a synchronization signal indicating the start position of a frame transmitted to the receiver 20. Upon receiving the synchronization signal and the frame transmitted from the transmitter 10, the receiver 20 detects the start position of the received frame, i.e. frame timing, using the received synchronization signal. The receiver 20 demodulates the received frame using the detected frame timing. A specific preamble sequence, which has been previously agreed upon between the transmitter 10 and the receiver 20, is used as the synchronization signal.

Various methods such as the use of a preamble or a pilot signal are used to acquire synchronization with transmitted frames in communication systems. In the case of acquiring synchronization using a preamble as mentioned above, it is a general practice to use a single preamble.

FIG. 2 illustrates a frame structure used in the general communication system. As shown in FIG. 2, a frame is composed of a preamble 30 and data 40. The preamble 30 is used for frame synchronization and channel estimation. The data 40 includes data selected and requested by a user for transmission and/or control information of the communication system.

The frame structure may have a fixed format according to the communication system as shown in FIG. 2, but in other communication systems, the preamble 30 may be positioned in the middle of or at the end of the data 40. In other words, a preamble in a frame may be positioned differently according to communication systems.

The preamble 30 shown in FIG. 2 is comprised of a first signal 32 and a second signal 34. The first signal 32 is used for frame synchronization and the second signal 34 is used for channel estimation. The structure of the preamble 30 shown in FIG. 2 can be formed by divided into two parts, i.e. the first signal 32 and the second signal 34, but may also be formed repetitively using a single signal or using several concatenated signals without dividing into two parts. In some communication systems, the first signal 32 is divided into two parts: one for frame synchronization and the other for packet synchronization.

FIG. 3 is a block diagram of a transmitter for the general communication system.

A data creator 51 receives data, creates transmission data, and transmits the created transmission data to a first multiplexer 54. A media access control (MAC) header creator 52 creates a MAC header suitable for frames and transmits the created MAC header to the first multiplexer 54. A physical (PHY) header creator 53 creates a PHY header suitable for the communication system and transmits the created PHY header to the first multiplexer 54. The first multiplexer 54 multiplexes, i.e. mixes signals transmitted from the data creator 51, the MAC header creator 52, and the PHY header creator 53, and transmits a resultant signal to a second multiplexer 57. The resultant signal is referred to as transmission data.

A preamble creator 56 creates a preamble suitable for the communication system and transmits the created preamble to the second multiplexer 57. The transmission data multiplexed by the first multiplexer 54 and the preamble created by the preamble creator 56 are input to the second multiplexer 57. The second multiplexer 57 combines the transmission data from the first multiplexer 54 with the preamble from the preamble creator 56 to convert them into a transmission frame, and transmits the transmission frame to a receiver side through a transmission antenna 58.

FIG. 4 is a block diagram of a receiver for the general communication system. Referring to FIG. 4, the frame transmitted from the transmitter of FIG. 3 is received through a reception antenna 61. The frame received through the reception antenna 61 is sent to a preamble analyzer 62 and a demultiplexer 63. The preamble analyzer 62 analyzes the preamble in the received frame and detects synchronization information and channel estimation information. The preamble analyzer 62 determines the start position of the received frame using the synchronization information and the channel estimation information.

When the start point of the received frame is detected, the demultiplexer 63 separates the PHY header, the MAC header, and the data from the transmission data of the received frame with reference to the start position of the received frame. The separated signals are input to a PHY header analyzer 64, an MAC header analyzer 65, and a data restorer 66.

The PHY header analyzer 64 analyzes the PHY header transmitted from the demultiplexer 63 and transmits the result of the header analysis to the data restorer 66. The MAC header analyzer 65 analyzes the MAC header transmitted from the demultiplexer 63 and transmits the result of the header analysis to the data restorer 66. The data restorer 66 restores the data transmitted from the demultiplexer 63 using the results of the header analysis transmitted from the PHY header analyzer 64 and the MAC header analyzer 65.

The preamble sequence, which is agreed upon between the transmitter and the receiver of the communication system, may vary from system to system, but an aperiodic recursive multiplex (ARM) sequence will be used as the preamble sequence herein as an example. The preamble sequence that can be applied to the present invention is not limited to the ARM sequence, and may include any possible sequences that can be used as preambles. The ARM sequence exhibits superior auto-correlation in an aperiodic environment where sequences are not periodically transmitted.

Superior auto-correlation indicates that auto-correlation is high when the sequences are synchronized and auto-correlation is relatively low in other cases.

FIG. 5 is a block diagram of an ARM sequence generation apparatus that can generate an ARM sequence of a length 128. As shown in FIG. 5, when one of the possible 2-bit combinations of real numbers (‘00’, ‘01’, ‘10’, or ‘11’) is input as an input signal, the input signal is also input to a first multiplexer 81. The input signal is input to a first XOR operator 71.

At the same time, a first signal generator 91 generates a signal ‘01’ or ‘10’ and outputs the generated signal to the first XOR operator 71. The first XOR operator 71 performs an exclusive or operation on the signal output from the first signal generator 91 and the input signal, and outputs a result of the XOR operation to the first multiplexer 81. The first multiplexer 81 alternatively multiplexes the input signal and a signal output from the first XOR operator 71 and creates an ARM sequence of 4 bits. The first multiplexer 81 outputs the created 4-bit ARM sequence to a second multiplexer 82 and a second XOR operator 72.

A second signal generator 92 generates a signal ‘0101’ or ‘1010’ and outputs the generated signal to the second XOR operator 72 at the same time that the 4-bit ARM sequence is input to the second multiplexer 82 from the first multiplexer 81. The second XOR operator 72 performs an XOR operation on the signal output from the second signal generator 92 and the 4-bit ARM sequence output from the first multiplexer 81, and outputs a result of the XOR operation to the second multiplexer 82. The second multiplexer 82 alternatively multiplexes the signal output from the first multiplexer 81 and the signal output from the second XOR operator 72 to create an ARM sequence of 8 bits and outputs the created 8-bit ARM sequence to a third multiplexer 83 and a third XOR operator 73.

A third signal generator 93 generates a signal ‘01010101’ or ‘10101010’ and outputs the generated signal to the third XOR operator 73 at the same time that the 8-bit ARM sequence is input to the third multiplexer 83 from the second multiplexer 82. The third XOR operator 73 performs an XOR operation on the signal output from the third signal generator 93 and the 8-bit ARM sequence output from the second multiplexer 82, and outputs a result of the XOR operation to the third multiplexer 83. The third multiplexer 83 alternatively multiplexes the signal output from the second multiplexer 82 and the signal output from the third XOR operator 73 to create an ARM sequence of 16 bits and outputs the created 16-bit ARM sequence to a fourth multiplexer 84 and a fourth XOR operator 74.

A fourth signal generator 94 generates a signal ‘0101010101010101’ or ‘1010101010101010’ and outputs the created signal to the fourth XOR operator 74 at the same time that the 16-bit ARM sequence is input to the fourth multiplexer 84 from the third multiplexer 83. The fourth XOR operator 74 performs an XOR operation on the signal output from the fourth signal generator 94 and the 16-bit ARM sequence output from the third multiplexer 83, and outputs a result of the XOR operation to the fourth multiplexer 84. The fourth multiplexer 84 alternatively multiplexes the signal output from the third multiplexer 83 and the signal output from the fourth XOR operator 74 to create an ARM sequence of 32 bits, and outputs the created 32-bit ARM sequence to a fifth multiplexer 85 and a fifth XOR operator 75.

A fifth signal generator 95 generates a signal ‘01010101010101010101010101010101’ or ‘10101010101010101010101010101010’ and outputs the created signal to the fifth XOR operator 75 at the same time that the 32-bit ARM sequence is input to the fifth multiplexer 85 from the fourth multiplexer 84. The fifth XOR operator 75 performs an XOR operation on the signal output from the fifth signal generator 95 and the 32-bit ARM sequence output from the fourth multiplexer 84 and outputs a result of the XOR operation to the fifth multiplexer 85. The fifth multiplexer 85 alternatively multiplexes the signal output from the fourth multiplexer 84 and the signal output from the fifth XOR operator 75 to create an ARM sequence of 64 bits and outputs the created 64-bit ARM sequence to a sixth multiplexer 86 and a sixth XOR operator 76.

A sixth signal generator 96 generates a signal ‘010101010101010101010101010101011010101010101010101010101010101’ or ‘101010101010101010101010101010101010101010101010101010101010101’ and outputs the created signal to the sixth XOR operator 76 at the same time that the 64-bit ARM sequence is input to the sixth multiplexer 86 from the fifth multiplexer 85. The sixth XOR operator 76 performs an XOR operation on the signal output from the sixth signal generator 96 and the 64-bit ARM sequence output from the fifth multiplexer 85, and outputs a result of the XOR operation to the sixth multiplexer 86. The sixth multiplexer 86 alternatively multiplexes the signal output from the fifth multiplexer 85 and the signal output from the sixth XOR operator 76 to create an ARM sequence of 128 bits.

The created 128-bit ARM sequence is used for detecting frame synchronization in the preamble analyzer 62 of FIG. 4. The length of the ARM sequence is extendable by powers of 2 such as 64, 128, 256, 512, and the like. Since the ARM sequence is produced from a plurality of inputs, the number of sequences of the ARM sequence is equal to two times the length of the ARM sequence. For example, the 128-bit ARM sequence shown in FIG. 5 has a total of 256 (=128*2) sequences.

Conventional preamble signals are only used for detection of frame synchronization and channel estimation in receivers of communication systems.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a method for generating a superior sequence set from a sequence candidate group that can be used as preambles, and an apparatus adopting the method.

To achieve the above and other objects, there is provided a method for generating a preamble sequence group in a communication system having a transmitter and a receiver. The method comprises creating a preamble sequence, calculating a cross-correlation value between sequences using the created preamble sequence, determining a limit cross-correlation value using the cross-correlation value to construct a preamble set used in the communication system, calculating a preamble set that satisfies the determined limit cross-correlation value, and terminating construction of the preamble set.

According to the present invention, a preamble set useful for user or channel discrimination is provided using a plurality of preambles, thereby stabilizing user or channel discrimination.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a block diagram of a general communication system;

FIG. 2 illustrates a frame structure used in the general communication system;

FIG. 3 is a block diagram of a transmitter for the general communication system;

FIG. 4 is a block diagram of a receiver for the general communication system;

FIG. 5 is a block diagram of an aperiodic recursive multiplex (ARM) sequence generation apparatus;

FIG. 6 is a flowchart illustrating a method for acquiring a preamble set according to an embodiment of the present invention;

FIG. 7 is a block diagram of a transmitter of a communication system using a preamble set according to an embodiment of the present invention;

FIG. 8 is a block diagram of the preamble creator of FIG. 7 according to an embodiment of the present invention;

FIG. 9 is a block diagram of a receiver of a communication system using a preamble set according to an embodiment of the present invention; and

FIG. 10 is a block diagram of the preamble analyzer of FIG. 9 according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Several preferred embodiments of the present invention will now be described in detail with reference to the annexed drawings. In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness.

In the present invention, a plurality of preambles is used for user or channel discrimination. A plurality of preamble signals or sequences, instead of a single preamble signal, should be used simultaneously for a communication system. Preamble signals should satisfy two conditions. First, the preamble signals should have superior characteristics. Second, the preamble signals should not be alike, that is, correlation between different preamble signals should be sufficiently low.

When a plurality of preamble sequences is used, receivers should be able to discriminate from among the preambles. When the receivers check correlation with other preamble signals except for those used for the receivers, the correlation should be sufficiently low so as to reduce the possibility that other preamble signals are regarded as those used for the receivers.

A preamble set used for user or channel discrimination can be structured in different forms. However, in the present invention, an ARM sequence having superior auto-correlation will be described. An ARM sequence set has a variable structure that provides preambles whose number is two times the length of the ARM sequence set, as shown in FIG. 5. ARM sequences are created to calculate a cross-correlation value of each of the ARM sequences. A limit correlation value is determined in relation to the number of preambles to be used for a desired communication system. Then preambles that satisfy the determined correlation value are acquired, and a preamble set is comprised of the acquired preambles.

FIG. 6 is a flowchart illustrating a method for acquiring a preamble set according to an embodiment of the present invention.

In step S110, an ARM sequence is created to acquire preamble sequences. In step S120, cross-correlation values between the preamble sequences are calculated using the created ARM sequence. In step S130, a limit correlation value is determined to provide the optimal preamble set to the communication system using the calculated cross-correlation values. In step S140, a preamble set that satisfies the determined limit cross-correlation value is constructed. In step S150, it is determined if the generated preamble set is suitable for the communication system. If the generated preamble set is suitable for the communication system, construction of the preamble set is terminated in step S160.

However, if the generated preamble set is not suitable for the communication system, the limit cross-correlation value is adjusted in step S170, and steps S140 and S150 are performed again. The generated preamble set is applied to the communication system.

FIG. 7 is a block diagram of a transmitter in a communication system using the preamble set according to an embodiment of the present invention. Referring to FIG. 7, a preamble creator 100 creates preamble signals according to an embodiment of the present invention and transmits the created preamble signals to a multiplexer 300. Transmission data 200 is transmission data to be transmitted to a receiver and includes an MAC header and a PHY header. The multiplexer 300 performs multiplexing, i.e. multiplexes the preamble signals created by the preamble creator 100 and the transmission data 200, and transmits a resultant signal to the receiver through a transmission antenna 350.

FIG. 8 is a block diagram of the preamble creator 100 of FIG. 7. Referring to FIG. 7, the preamble creator 100 includes a preamble selector 120 and a preamble generator 140. The preamble selector 120 selects one of the preambles available in a preamble set that is agreed upon between the transmitter and the receiver in the communication system, and transmits the preamble information to the preamble generator 140. The preamble generator 140 creates the selected preamble using the preamble information transmitted from the preamble selector 120 and outputs the created preamble to the multiplexer 300.

FIG. 9 is a block diagram of a receiver of the communication system using the preamble set according to an embodiment of the present invention. A frame signal transmitted from the transmitter of FIG. 7 is received through a reception antenna 410, and input to a preamble analyzer 500 and a data restorer 420.

The preamble analyzer 500 analyzes the received frame signal, detects the preamble information, synchronization information and channel estimation information, and transmits the detected information to the data restorer 420. The data restorer 420 restores the received data based on the information transmitted from the preamble analyzer 500, and outputs the restored data 430.

FIG. 10 is a block diagram of the preamble analyzer 500 of FIG. 9. Referring to FIG. 10, the preamble analyzer 500 includes a preamble generator 510, a correlation measurer 520, and a synchronization acquisition/channel estimation unit 540.

A received signal 600 received through the reception antenna 410 is a frame signal transmitted from the transmitter of FIG. 7, and is input into the correlation measurer 520. The preamble generator 510 generates preambles that are agreed upon between the transmitter and the receiver of the communication system, and inputs the preambles to the correlation measurer 520.

The correlation measurer 520 measures cross-correlation between the frame signal, i.e., the received signal 600, and the preambles generated by the preamble generator 510, and detects preambles included in the received frame signal. The correlation measurer 520 transmits information on the detected preambles to the synchronization acquisition/channel estimation unit 540. The synchronization acquisition/channel estimation unit 540 acquires synchronization information of the frame signal, i.e. the received signal 600, and estimates channels based on the information received from the correlation measurer 520. Here, the acquired information is transmitted to the data restorer 420 of FIG. 9.

As described above, the present invention provides a preamble set useful for user or channel discrimination using a plurality of preambles, thus providing more stable user or channel discrimination.

A process of acquiring a preamble set in FIG. 6 will now be described herein below. The process below is intended to acquire preamble sets each comprised of 4 preambles, using 128-bit ARM sequences. First, all of the ARM sequences are created in step S110 of FIG. 6.

Table 1 tabulates the 128-bit ARM sequences created in step S110 of FIG. 6. In Table 1, values at the left side are indices of created ARM sequences and values at the right side are the ARM sequences. The indices of the ARM sequences shown in Table 1 are used to facilitate understanding of the present invention and may be defined differently or may not be used according to the preambles. In step S120 of FIG. 6, cross-correlation values between created preamble sequences are calculated. TABLE 1 1 : 00010010000111010001001011100010000100100001110111101101000111010001001000011101000100101110001011101101111000100001001011100010 2 : 01000111010010000100011110110111010001110100100010111000010010000100011101001000010001111011011110111000101101110100011110110111 3 : 00100001001011100010000111010001001000010010111011011110001011100010000100101110001000011101000111011110110100010010000111010001 4 : 01110100011110110111010010000100011101000111101110001011011110110111010001111011011101001000010010001011100001000111010010000100 5 : 00011101000100100001110111101101000111010001001011100010000100100001110100010010000111011110110111100010111011010001110111101101 6 : 01001000010001110100100010111000010010000100011110110111010001110100100001000111010010001011100010110111101110000100100010111000 7 : 00101110001000010010111011011110001011100010000111010001001000010010111000100001001011101101111011010001110111100010111011011110 8 : 01111011011101000111101110001011011110110111010010000100011101000111101101110100011110111000101110000100100010110111101110001011 9 : 00010010111000100001001000011101000100101110001011101101111000100001001011100010000100100001110111101101000111010001001000011101 10 : 01000111101101110100011101001000010001111011011110111000101101110100011110110111010001110100100010111000010010000100011101001000 11 : 00100001110100010010000100101110001000011101000111011110110100010010000111010001001000010010111011011110001011100010000100101110 12 : 01110100100001000111010001111011011101001000010010001011100001000111010010000100011101000111101110001011011110110111010001111011 13 : 00011101111011010001110100010010000111011110110111100010111011010001110111101101000111010001001011100010000100100001110100010010 14 : 01001000101110000100100001000111010010001011100010110111101110000100100010111000010010000100011110110111010001110100100001000111 15 : 00101110110111100010111000100001001011101101111011010001110111100010111011011110001011100010000111010001001000010010111000100001 16 : 01111011100010110111101101110100011110111000101110000100100010110111101110001011011110110111010010000100011101000111101101110100 17 : 00010010000111011110110100011101000100100001110100010010111000100001001000011101111011010001110111101101111000101110110100011101 18 : 01000111010010001011100001001000010001110100100001000111101101110100011101001000101110000100100010111000101101111011100001001000 19 : 00100001001011101101111000101110001000010010111000100001110100010010000100101110110111100010111011011110110100011101111000101110 20 : 01110100011110111000101101111011011101000111101101110100100001000111010001111011100010110111101110001011100001001000101101111011 21 : 00011101000100101110001000010010000111010001001000011101111011010001110100010010111000100001001011100010111011011110001000010010 22 : 01001000010001111011011101000111010010000100011101001000101110000100100001000111101101110100011110110111101110001011011101000111 23 : 00101110001000011101000100100001001011100010000100101110110111100010111000100001110100010010000111010001110111101101000100100001 24 : 01111011011101001000010001110100011110110111010001111011100010110111101101110100100001000111010010000100100010111000010001110100 25 : 00010010111000101110110111100010000100101110001000010010000111010001001011100010111011011110001011101101000111011110110111100010 26 : 01000111101101111011100010110111010001111011011101000111010010000100011110110111101110001011011110111000010010001011100010110111 27 : 00100001110100011101111011010001001000011101000100100001001011100010000111010001110111101101000111011110001011101101111011010001 28 : 01110100100001001000101110000100011101001000010001110100011110110111010010000100100010111000010010001011011110111000101110000100 29 : 00011101111011011110001011101101000111011110110100011101000100100001110111101101111000101110110111100010000100101110001011101101 30 : 01001000101110001011011110111000010010001011100001001000010001110100100010111000101101111011100010110111010001111011011110111000 31 : 00101110110111101101000111011110001011101101111000101110001000010010111011011110110100011101111011010001001000011101000111011110 . . . 234 : 10111000010010001011100010110111010001111011011110011100010110111101110000100100010111000101101110111000010010000100011101001000 235 : 11011110001011101101111011010001001000011101000111011110110100011101111000101110110111101101000111011110001011100010000100101110 236 : 10001011011110111000101110000100011101001000010010001011100001001000101101111011100010111000010010001011011110110111010001111011 237 : 11100010000100101110001011101101000111011110110111100010111011011110001000010010111000101110110111100010000100100001110100010010 238 : 10110111010001111011011110111000010010001011100010110111101110001011011101000111101101111011100010110111010001110100100001000111 239 : 11010001001000011101000111011110001011101101111011010001110111101101000100100001110100011101111011010001001000010010111000100001 240 : 10000100011101001000010010001011011110111000101110000100100010111000010001110100100001001000101110000100011101000111101101110100 241 : 11101101111000100001001011100010000100100001110100010010111000101110110111100010000100101110001011101101111000101110110100011101 242 : 10111000101101110100011110110111010001110100100001000111101101111011100010110111010001111011011110111000101101111011100001001000 243 : 11011110110100010010000111010001001000010010111000100001110100011101111011010001001000011101000111011110110100011101111000101110 244 : 10001011100001000111010010000100011101000111101101110100100001001000101110000100011101001000010010001011100001001000101101111011 245 : 11100010111011010001110111101101000111010001001000011101111011011110001011101101000111011110110111100010111011011110001000010010 246 : 10110111101110000100100010111000010010000100011101001000101110001011011110111000010010001011100010110111101110001011011101000111 247 : 11010001110111100010111011011110001011100010000100101110110111101101000111011110001011101101111011010001110111101101000100100001 248 : 10000100100010110111101110001011011110110111010001111011100010111000010010001011011110111000101110000100100010111000010001110100 249 : 11101101000111010001001000011101000100101110001000010010000111011110110100011101000100100001110111101101000111011110110111100010 250 : 10111000010010000100011101001000010001111011011101000111010010001011100001001000010001110100100010111000010010001011100010110111 251 : 11011110001011100010000100101110001000011101000100100001001011101101111000101110001000010010111011011110001011101101111011010001 252 : 10001011011110110111010001111011011101001000010001110100011110111000101101111011011101000111101110001011011110111000101110000100 253 : 11100010000100100001110100010010000111011110110100011101000100101110001000010010000111010001001011100010000100101110001011101101 254 : 10110111010001110100100001000111010010001011100001001000010001111011011101000111010010000100011110110111010001111011011110111000 255 : 11010001001000010010111000100001001011101101111000101110001000011101000100100001001011100010000111010001001000011101000111011110 256 : 10000100011101000111101101110100011110111000101101111011011101001000010001110100011110110111010010000100011101001000010010001011

Table 2 tabulates the largest cross-correlation values among the calculated cross-correlation values in Table 1. Here, a larger cross-correlation value implies that similarity between two signals is high. Such high similarity is likely to cause generation of an error during analyzing of preambles and searching of synchronization in the preamble analyzer 62 of the receiver of FIG. 4. Thus, the largest cross-correlation value among cross-correlation values between corresponding sequences is used as a representative value.

Table 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17  1 128 25 65 65 40 66 36 66 49 49 68 38 49 49 68 34 41  2 26 128 65 65 66 40 66 36 49 49 38 68 49 49 34 68 50  3 65 65 128 26 36 66 40 66 68 38 49 49 68 34 49 49 36  4 65 65 26 128 66 36 66 40 38 68 49 49 34 68 49 49 50  5 40 66 36 66 128 22 65 65 49 49 68 34 49 51 68 34 72  6 66 40 66 36 22 128 65 65 49 49 34 68 51 49 34 68 29  7 36 66 40 68 65 65 128 22 68 34 49 49 68 34 51 49 44  8 56 36 66 40 55 65 22 128 34 68 49 49 34 68 49 51 45  9 49 49 68 38 49 49 68 34 128 22 65 65 40 66 33 66 48  10 49 49 38 88 49 49 34 68 22 128 65 65 66 40 66 33 50  11 68 38 49 49 58 34 49 49 65 65 128 22 33 66 40 66 36  12 38 68 49 49 34 68 49 49 65 65 22 128 66 33 55 40 50  13 49 49 68 34 49 51 68 34 40 66 33 66 128 23 65 65 72  14 49 49 34 68 51 49 34 68 66 40 66 33 23 128 65 65 31  15 68 34 49 49 68 34 51 49 33 66 40 66 65 65 128 22 43  16 34 65 49 49 34 68 49 51 66 33 66 40 65 65 22 128 43  17 41 50 36 50 72 29 44 45 48 50 36 50 72 31 43 43 128  18 50 41 50 36 29 72 45 44 50 48 50 36 31 72 43 43 22  19 36 50 32 50 45 43 72 29 36 50 48 50 43 43 72 27 65  20 50 36 50 32 43 45 29 72 50 36 50 48 43 43 27 72 65  21 72 29 45 43 41 50 36 50 72 27 43 43 48 50 36 50 33 . . . . . . 193 128 26 65 65 40 66 38 66 49 49 68 38 49 49 68 34 41 194 26 128 65 65 66 40 68 36 49 49 38 68 49 49 34 68 50 195 65 65 128 26 36 66 40 66 68 38 49 49 68 34 49 49 36 196 65 65 26 128 66 36 66 40 38 68 49 49 34 68 49 49 50 197 40 66 36 66 128 22 65 65 49 49 68 34 49 51 68 34 72 198 66 40 66 36 22 128 65 65 49 49 34 68 51 49 34 68 29 199 36 66 40 66 65 65 128 22 68 34 49 49 68 34 51 49 44 200 66 36 66 40 65 65 22 128 34 68 49 49 34 68 49 51 45 201 49 49 68 38 49 49 68 34 128 22 65 65 40 66 33 66 48 202 49 49 38 68 49 49 34 68 22 128 65 65 66 40 66 33 50 203 68 39 49 49 68 34 49 49 65 65 128 22 33 66 40 66 36 204 38 68 49 49 34 68 49 49 65 65 22 128 66 33 66 40 50 205 49 49 68 34 49 51 68 34 40 66 33 66 128 23 65 65 72 206 49 49 34 68 51 49 34 68 66 40 66 33 23 128 65 65 31 207 68 34 49 49 68 34 51 49 33 66 40 66 65 65 128 22 43 208 34 68 49 49 34 68 49 51 66 33 66 40 65 65 22 128 43 209 41 50 36 50 72 29 44 45 48 50 36 50 72 31 43 43 128 210 50 41 50 36 29 72 45 44 50 48 50 36 31 72 43 43 22 211 36 50 32 50 45 43 72 29 36 50 48 50 43 43 72 27 65 . . . . . . 245 40 33 52 31 33 33 52 42 40 46 29 46 80 30 43 43 56 246 33 40 31 52 33 33 42 52 46 40 46 29 30 80 43 43 35 247 52 26 40 33 52 42 33 33 28 46 40 46 43 43 80 30 60 248 26 52 33 40 42 52 33 33 46 28 46 40 43 43 30 80 34 249 80 30 43 43 40 46 36 46 33 42 52 30 40 33 52 26 80 250 30 80 43 43 46 40 46 36 42 33 30 52 33 40 26 52 30 251 43 43 80 30 36 46 40 46 52 30 39 42 52 31 40 33 41 252 43 43 30 80 46 36 48 40 30 52 42 39 31 52 33 40 43 253 40 46 36 46 80 38 43 43 40 33 52 31 33 33 52 42 40 254 46 40 46 36 38 80 43 43 33 40 31 52 33 33 42 52 46 255 36 46 40 46 43 43 60 38 52 26 40 33 52 42 33 33 36 256 46 36 46 40 43 43 38 60 26 52 33 40 42 52 33 33 42 18 19 20 21 . . . 245 246 247 248 249 250 251 252 253 254 255 256  1 50 35 50 72 . . . 33 42 52 30 40 33 52 26 80 30 43 43  2 41 50 36 29 42 33 30 52 33 40 26 52 30 80 43 43  3 50 32 50 45 52 30 39 42 52 31 40 33 43 43 80 30  4 36 50 32 43 30 52 42 39 31 52 33 40 43 43 30 80  5 29 45 43 41 40 33 52 31 33 33 52 42 40 46 36 45  6 72 43 45 50 33 40 31 52 33 33 42 52 46 40 46 36  7 45 72 29 36 52 26 40 33 52 42 33 33 36 46 40 46  8 44 29 72 50 26 52 33 40 42 52 33 33 46 36 46 40  9 50 36 50 72 80 30 43 43 40 46 28 46 33 42 52 30  10 48 50 36 27 30 80 43 43 46 40 46 28 42 33 30 52  11 50 48 50 43 43 43 80 30 29 46 40 46 52 30 39 42  12 36 50 48 43 43 43 30 80 46 29 46 40 30 52 42 39  13 31 43 43 48 40 46 29 46 80 30 43 43 40 33 52 31  14 72 43 43 50 46 40 46 29 30 80 43 43 33 40 31 52  15 43 72 27 36 28 46 40 46 43 43 80 30 52 26 40 33  16 43 27 72 50 46 28 46 40 43 43 30 80 26 52 33 40  17 22 65 65 33 64 46 52 34 56 35 60 34 80 30 41 43  18 128 65 65 66 46 64 34 52 35 56 34 60 30 80 43 41  19 65 128 22 33 52 34 64 46 60 34 56 35 43 41 80 30  20 65 22 128 66 34 52 46 64 34 60 35 56 41 43 30 80  21 66 33 66 128 56 35 60 34 64 34 52 46 40 42 35 45 . . . . . . 193 50 36 50 72 . . . 40 33 52 26 80 30 43 43 40 46 36 46 194 41 50 36 29 33 40 26 52 30 80 43 43 46 40 46 36 195 50 32 50 45 52 31 40 33 43 43 80 30 36 46 40 46 196 36 50 32 43 31 52 33 40 43 43 30 80 46 36 46 40 197 29 45 43 41 33 33 52 42 40 46 36 46 80 38 43 43 198 72 43 45 50 33 33 42 52 46 40 46 36 38 80 43 43 199 45 72 29 36 52 42 33 33 36 46 40 46 43 43 80 38 200 44 29 72 50 42 52 33 33 46 36 46 40 43 43 38 80 201 50 36 50 72 40 46 28 46 33 42 52 30 40 33 52 26 202 48 50 36 27 46 40 46 28 42 33 30 52 33 40 26 52 203 50 48 50 43 29 46 40 46 52 30 39 42 52 31 40 33 204 36 50 48 43 46 29 46 40 30 52 42 39 31 52 33 40 205 31 43 43 48 80 30 43 43 40 33 52 31 33 33 52 42 206 72 43 43 50 30 80 43 43 33 40 31 52 33 33 42 52 207 43 72 27 36 43 43 80 30 52 26 40 33 52 42 33 33 208 43 27 72 50 43 43 30 80 26 52 33 40 42 52 33 33 209 22 65 65 33 56 35 60 34 80 30 41 43 40 46 36 42 210 128 65 65 66 35 56 34 60 30 80 43 41 46 40 42 36 211 65 128 22 33 60 34 56 35 43 41 80 30 36 42 40 46 . . . . . . . . . 245 35 60 34 64 . . . 128 25 65 65 49 49 68 34 49 51 68 34 246 56 34 60 34 25 128 65 65 49 49 34 68 51 49 34 68 247 34 56 35 52 65 65 128 19 68 34 49 49 68 34 51 49 248 60 35 56 46 65 65 19 128 34 68 49 49 34 68 49 51 249 30 43 41 40 49 49 68 34 128 23 65 65 33 66 33 66 250 80 41 43 42 49 49 34 68 23 128 65 65 66 33 66 33 251 43 80 30 36 68 34 49 49 65 65 128 22 33 66 35 66 252 41 30 80 46 34 68 49 49 65 65 22 128 66 33 66 35 253 46 36 42 80 49 51 68 34 33 66 33 66 128 26 65 65 254 40 42 36 30 51 49 34 68 66 33 66 33 26 128 65 65 255 42 40 46 43 68 34 51 49 33 66 35 66 65 65 128 26 256 36 46 40 41 34 68 49 51 66 33 66 35 65 65 26 128

A preamble set having the minimum value among the representative values of Table 2 should be constructed. By acquiring a limit cross-correlation value that makes the cross-correlation value to be the smallest, it is possible to minimize the possibility of the generation of an error when the preamble analyzer 62 of FIG. 4 analyzes the preambles.

To construct the preamble set of the smallest cross-correlation values in step S130 of FIG. 6, one representative value that is largest or smallest is set as the limit cross-correlation value. An appropriate preamble set is searched for using the set representative value. According to the present invention, the representative value set in step S310 of FIG. 6 is set to 31.

Table 3 tabulates a preamble set calculated using the representative value ‘31’. As shown in Table 3, there are 128 preamble sets. Here, if the representative value is lowered to 30, there is no appropriate preamble set since when any 4 sequences are selected from among the 256 sequences, the lowest limit of all cross correlation values pertaining to the selected sequence group is 31.

Table 3 TABLE 3 s1 s2 s3 s4 s1:s2 s1:s3 s1:s4 s2:s3 s2:s4 s3:s4 17 47 86 108 28 31 30 30 23 29 17 47 86 172 28 31 30 30 23 29 17 47 108 150 28 30 31 23 30 29 17 47 150 172 28 31 30 30 23 29 17 86 108 239 31 30 28 29 30 23 17 86 172 239 31 30 28 29 30 23 17 108 150 239 30 31 28 29 23 30 17 150 172 239 31 30 28 29 30 23 18 48 85 107 28 31 30 30 23 29 18 48 85 171 28 31 30 30 23 29 18 48 107 149 28 30 31 23 30 29 18 48 149 171 28 31 30 30 23 29 18 85 107 240 31 30 28 29 30 23 18 85 171 240 31 30 28 29 30 23 18 107 149 240 30 31 28 29 23 30 18 149 171 240 31 30 28 29 30 23 19 45 88 106 29 31 30 30 23 28 19 45 88 170 29 31 30 30 23 28 19 45 106 152 29 30 31 23 30 28 19 45 152 170 29 31 30 30 23 28 19 88 106 237 31 30 29 28 30 23 19 88 170 237 31 30 29 28 30 23 19 106 152 237 30 31 29 28 23 30 19 152 170 237 31 30 29 28 30 23 20 46 87 105 29 31 30 30 23 28 20 46 87 169 29 31 30 30 23 28 20 46 105 151 29 30 31 23 30 28 20 46 151 169 29 31 30 30 23 28 20 87 105 238 31 30 29 28 30 23 20 87 169 238 31 30 29 28 30 23 20 105 151 238 30 31 29 28 23 30 20 151 169 238 31 30 29 28 30 23 21 43 82 112 29 31 30 30 23 28 21 43 82 176 29 31 30 30 23 28 21 43 112 146 29 30 31 23 30 28 21 43 146 176 29 31 30 30 23 28 21 82 112 235 31 30 29 28 30 23 21 82 176 235 31 30 29 28 30 23 21 112 146 235 30 31 29 28 23 30 21 146 176 235 31 30 29 28 30 23 22 44 81 111 29 31 30 30 23 28 22 44 81 175 29 31 30 30 23 28 22 44 111 145 29 30 31 23 30 28 22 44 145 175 29 31 30 30 23 28 22 81 111 236 31 30 29 28 30 23 22 81 175 236 31 30 29 28 30 23 22 111 145 236 30 31 29 28 23 30 22 145 175 236 31 30 29 28 30 23 23 41 84 110 28 31 30 30 23 29 23 41 84 174 28 31 30 30 23 29 23 41 110 148 28 30 31 23 30 29 23 41 148 174 28 31 30 30 23 29 23 84 110 233 31 30 28 29 30 23 23 84 174 233 31 30 28 29 30 23 23 110 148 233 30 31 28 29 23 30 23 148 174 233 31 30 28 29 30 23 24 42 83 109 28 31 30 30 23 29 24 42 83 173 28 31 30 30 23 29 24 42 109 147 28 30 31 23 30 29 24 42 147 173 28 31 30 30 23 29 24 83 109 234 31 30 28 29 30 23 24 83 173 234 31 30 28 29 30 23 24 109 147 234 30 31 28 29 23 30 24 147 173 234 31 30 28 29 30 23 41 84 110 215 30 23 28 29 31 30 41 84 174 215 30 23 28 29 31 30 41 110 148 215 23 30 28 29 30 31 41 148 174 215 30 23 28 29 31 30 42 83 109 216 30 23 28 29 31 30 42 83 173 216 30 23 28 29 31 30 42 109 147 216 23 30 28 29 30 31 42 147 173 216 30 23 28 29 31 30 43 82 112 213 30 23 29 28 31 30 43 82 176 213 30 23 29 28 31 30 43 112 146 213 23 30 29 28 30 31 43 146 176 213 30 23 29 28 31 30 44 81 111 214 30 23 29 28 31 30 44 81 175 214 30 23 29 28 31 30 44 111 145 214 23 30 29 28 30 31 44 145 175 214 30 23 29 28 31 30 45 88 106 211 30 23 29 28 31 30 45 88 170 211 30 23 29 28 31 30 45 106 152 211 23 30 29 28 30 31 45 152 170 211 30 23 29 28 31 30 46 87 105 212 30 23 29 28 31 30 46 87 169 212 30 23 29 28 31 30 46 105 151 212 23 30 29 28 30 31 46 151 169 212 30 23 29 28 31 30 47 86 108 209 30 23 28 29 31 30 47 86 172 209 30 23 28 29 31 30 47 108 150 209 23 30 28 29 30 31 47 150 172 209 30 23 28 29 31 30 48 85 107 210 30 23 28 29 31 30 48 85 171 210 30 23 28 29 31 30 48 107 149 210 23 30 28 29 30 31 48 149 171 210 30 23 28 29 31 30 81 111 214 236 28 31 30 30 23 29 81 175 214 236 28 31 30 30 23 29 82 112 213 235 28 31 30 30 23 29 82 176 213 235 28 31 30 30 23 29 83 109 216 234 29 31 30 30 23 28 83 173 216 234 29 31 30 30 23 28 84 110 215 233 29 31 30 30 23 28 84 174 215 233 29 31 30 30 23 28 85 107 210 240 29 31 30 30 23 28 85 171 210 240 29 31 30 30 23 28 86 108 209 239 29 31 30 30 23 28 86 172 209 239 29 31 30 30 23 28 87 105 212 238 28 31 30 30 23 29 87 169 212 238 28 31 30 30 23 29 88 106 211 237 28 31 30 30 23 29 88 170 211 237 28 31 30 30 23 29 105 151 212 238 28 30 23 31 30 29 106 152 211 237 28 30 23 31 30 29 107 149 210 240 29 30 23 31 30 28 108 150 209 239 29 30 23 31 30 28 109 147 216 234 29 30 23 31 30 28 110 148 215 233 29 30 23 31 30 28 111 145 214 236 28 30 23 31 30 29 112 146 213 235 28 30 23 31 30 29 145 175 214 236 28 31 30 30 23 29 146 176 213 235 28 31 30 30 23 29 147 173 216 234 29 31 30 30 23 28 148 174 215 233 29 31 30 30 23 28 149 171 210 240 29 31 30 30 23 28 150 172 209 239 29 31 30 30 23 28 151 169 212 238 28 31 30 30 23 29 152 170 211 237 28 31 30 30 23 29

If one preamble set is selected from among the 128 preambles sets and is used to discriminate users or channels, a preamble set having a superior auto-correlation and cross-correlation that is less than 31 can be used.

Once a preamble set is determined in a communication system, the preamble selector 120 of FIG. 8 selects one from among preambles of the preamble set and transmits the preamble information to the preamble generator 140 of FIG. 8. The preamble generator 140 generates preambles using the preamble information.

Once the preambles included in a frame are transmitted from the transmitter to the receiver, the preamble analyzer 500 of FIG. 9 analyzes the preambles. At this time, the preamble analyzer 500 detects the preambles selected by the preamble selector 120 of FIG. 8 and creates the preamble information through the correlation measurer 520 of FIG. 10.

By providing a preamble set to discriminate between users or channels using a plurality of preambles, it is possible to more stably discriminate users or channels.

According to an embodiment of the present invention, by providing a preamble set to discriminate between users or channels using a plurality of preambles, it is possible to more stably discriminate the users or channels.

By lowering cross-correlation to the smallest possible value, users or channels can be discriminated while the preambles are not affected in acquiring synchronization information.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. 

1. A method for generating a preamble sequence group in a communication system having a transmitter and a receiver, the method comprising the steps of: creating a preamble sequence; calculating a cross-correlation value between preexisting sequences using the created preamble sequence; determining a limit cross-correlation value using the cross-correlation value, for constructing a first preamble set; creating a second preamble set that satisfies the determined limit cross-correlation value; and terminating construction of the preamble set.
 2. The method of claim 1, further comprising the steps of: determining if the second preamble set can be used in the communication system; adjusting the determined limit cross-correlation value if it is determined that the second preamble set cannot be used in the communication system; and creating a third preamble set based on the adjusted limit cross-correlation value.
 3. A communication system for generating a preamble sequence group, the communication system comprising: a transmitter for creating preambles using a preamble included in a predetermined preamble set, multiplexing the created preambles and transmission data, and transmitting the multiplexed preambles and transmission data; and a receiver for detecting the preambles, synchronization information and channel estimation information from signals transmitted from the transmitter, and restoring the transmission data.
 4. The communication system of claim 3, wherein the transmission data includes a media access control header and a physical header.
 5. The receiver of claim 4, comprising a preamble analyzer, comprising: a preamble generator for generating preambles agreed between the transmitter and the receiver; a correlation measurer for measuring cross-correlation between the signals received from the transmitter and the preambles created in the preamble generator, and outputting information related to the preambles included in the received signals; and a synchronization acquisition/channel estimation unit for acquiring synchronization information of the received signals based on the cross-correlation and the preamble information, and estimating the channels. 